Some motor vehicle doors comprise inner and outer panels having inwardly turned flanges which abut one another and are spot welded together.
There is also a requirement for the panes of glass to be as close as possible to the outer skin of the vehicle ("flush mounting"), for several reasons including aesthetics, and reduction of wind noise, and reduction of coefficient of vehicle drag.
Consequently, there has been an adaptation of previously used S section mouldings, wherein the mouth of one of the recesses engages over the spot welded flanges and the mouth of the other recess is provided with glass engaging lips which will guide and cushion the glass. The prior art includes the British Application No. A2118232 (Draftex), British Patent No. 1355303 (Porsche), British Patent No. 1356871 (Ford), U.S. Pat. No. 4,007,536 (Soderberg), U.S. Pat. No. 3,479,768 (Smadja), U.S. Pat. No. 2,933,342 (Bright) and the Australian Application No. 31892/84 (Schlegel). Most of the prior art referred to includes a metal membrane of some type which will stiffen the glass run channel, and for example the Soderberg U.S. Pat. No. 4,007,536 makes use of a spring steel core layer, the Australian Schlegel application No. 31892/84 utilises a wire carrier as its metal membrane, the Smadja U.S. Pat. No. 3,479,768 refers to a "corrosion proof metal strip with its surface partly cut out" and the strip is coated by extrusion with a suitable thickness of synthetic rubber or plastic. Smadja is the closest art known to the applicant. Bright U.S. Pat. No. 2,933,342 also discloses a window guide constructed from a blank of sheet metal bent into a channel shape, the blank being formed with a series of inwardly directed slots to assist in bending curved about a small radius.
It is known that in the motor industry, attempts have been made to utilise imperforate strips of steel and aluminium, but a difficulty is encountered if imperforate strips are used as the core of a glass run channel, in that the doors usually have a radius in the x-y plane (elevation), a radius in the x-z plane (plan) and also a twist. It is thus necessary not merely to bend the metal around a small radius but also to twist the metal core of the channel. If aluminium is used which is sufficiently soft to achieve this, then there is a possibility of deformation occurring inadvertently, and a consequential damage to the product which is difficult to correct. If wire, or wire retained strips are used, as in some instances then a difficulty is encountered in maintaining sufficient structural integrity (that is, stiffness and shape).
A product known as "pinch weld" is widely used in the automotive trade, and this product comprises a metal core which is formed as a "lanced-stretch section", that is, the metal core is lanced with a plurality of slits extending transversely but the slits do not extend for the full width of the section, and the imperforate part of the section is subsequently rolled to extend its length and open the slits up into slots. The core is then formed to a U shape, and is covered with a PVC or other polymeric material, but is so worked that the thin imperforate longitudinal portions are all snapped and the "pinch weld" then consists of discontinuous transversely extending metal bars or ribs which hold the cross-sectional shape of the product. However this technique is not suitable for use with a glass run channel, because it is necessary for the metal core to be continuous in order to retain sufficient structural rigidity and strength.